From xen-devel-bounces@lists.xen.org Wed Feb 19 09:00:15 2014 Received: (at maildrop) by bugs.xenproject.org; 19 Feb 2014 09:00:15 +0000 Received: from lists.xen.org ([50.57.142.19]) by bugs.xenproject.org with esmtp (Exim 4.80) (envelope-from ) id 1WG30p-0002UB-J5 for xen-devel-maildrop-Eithu9ie@bugs.xenproject.org; Wed, 19 Feb 2014 09:00:15 +0000 Received: from localhost ([127.0.0.1] helo=lists.xen.org) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1WG2vu-0007qB-Ol; Wed, 19 Feb 2014 08:55:10 +0000 Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1WG2vp-0007q6-Pc for xen-devel@lists.xen.org; Wed, 19 Feb 2014 08:55:08 +0000 Received: from [85.158.137.68:12952] by server-4.bemta-3.messagelabs.com id 3E/5E-04858-96174035; Wed, 19 Feb 2014 08:55:05 +0000 X-Env-Sender: JBeulich@suse.com X-Msg-Ref: server-3.tower-31.messagelabs.com!1392800104!2819333!1 X-Originating-IP: [130.57.49.28] X-SpamReason: No, hits=0.0 required=7.0 tests=sa_preprocessor: VHJ1c3RlZCBJUDogMTMwLjU3LjQ5LjI4ID0+IDQ4MDU=\n X-StarScan-Received: X-StarScan-Version: 6.9.16; banners=-,-,- X-VirusChecked: Checked Received: (qmail 16694 invoked from network); 19 Feb 2014 08:55:04 -0000 Received: from nat28.tlf.novell.com (HELO nat28.tlf.novell.com) (130.57.49.28) by server-3.tower-31.messagelabs.com with DHE-RSA-AES256-SHA encrypted SMTP; 19 Feb 2014 08:55:04 -0000 Received: from EMEA1-MTA by nat28.tlf.novell.com with Novell_GroupWise; Wed, 19 Feb 2014 08:55:03 +0000 Message-Id: <53047F74020000780011D8E4@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.2 Date: Wed, 19 Feb 2014 08:55:00 +0000 From: "Jan Beulich" To: "Yang Z Zhang" References: <20140210080314.GA758@deinos.phlegethon.org> <20140211090202.GC92054@deinos.phlegethon.org> <20140211115553.GB97288@deinos.phlegethon.org> <52FA2C63020000780011B201@nat28.tlf.novell.com> <52FA480D.9040707@eu.citrix.com> <52FCE8BE.8050105@eu.citrix.com> <52FCF90F020000780011C29A@nat28.tlf.novell.com> <20140213162022.GE82703@deinos.phlegethon.org> <5301F000020000780011CCE0@nat28.tlf.novell.com> <53022209.1060005@eu.citrix.com> <5302332D020000780011CEF1@nat28.tlf.novell.com> <53033544.2000409@eu.citrix.com> In-Reply-To: Mime-Version: 1.0 Content-Disposition: inline Cc: George Dunlap , "andrew.cooper3@citrix.com" , Tim Deegan , Donald D Dugger , "xen-devel@lists.xen.org" , Xiantao Zhang Subject: Re: [Xen-devel] [PATCH] Don't track all memory when enabling log dirty to track vram X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org >>> On 19.02.14 at 02:28, "Zhang, Yang Z" wrote: > George Dunlap wrote on 2014-02-18: >> On 02/18/2014 03:14 AM, Zhang, Yang Z wrote: >> perhaps my original patch is better which will check >> paging_mode_log_dirty(d) && log_global: >> >> It turns out that the reason I couldn't get a crash was because libxc >> was actually paying attention to the -EINVAL return value, and >> disabling and then re-enabling logdirty. That's what would happen >> before your dirty vram patch, and that's what happens after. And >> arguably, that's the correct behavior for any toolstack, given that the > interface returns an error. > > Agree. > >> >> This patch would actually change the interface; if we check this in, >> then if you enable logdirty when dirty vram tracking is enabled, you >> *won't* get an error, and thus *won't* disable and re-enable logdirty mode. >> So actually, this patch would be more disruptive. >> > > Jan, do you have any comment? This simplistic variant is just calling for problems. As was already said elsewhere on this thread, we should simply do the mode change properly: Track that a partial log-dirty mode is in use, and allow switching to global log-dirty mode (converting all entries to R/O). Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel